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Sealant Composition

a technology of composition and sealant, applied in the field of sealant fluid, can solve the problems of lower limit of the size of the void that can be filled, sealant composition may not be correctly placed in all the voids before it sets, and higher reaction rate between calcium carbonate and silicate solution

Inactive Publication Date: 2009-04-30
SCHLUMBERGER TECH CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention is a sealant composition that can be used to seal voids in a wellbore. The composition comprises an alkali metal silicate and a calcium-containing inorganic compound, where the calcium particles have a small size. The small size allows the fluid to penetrate into small fractures and pore spaces in the formation. The composition can be pumped down the wellbore and allowed to mix together before being injected into a void. The composition can be used in low temperature environments. The technical effect of the invention is to provide an effective and flexible sealant for sealing voids in a wellbore.

Problems solved by technology

These voids may be cracks in the cement, or microannuli between the casing and the cement or between the cement and the formation.
However, even with this technology there is a lower limit to the size of the voids that can be filled when using micro-fine cementing technology because of the particle size.
However the voids (microannuli, fractures and pores) in subterranean wells that the sealant composition needs to penetrate can be very small and narrow, and therefore the solid particles in sealant compositions need to be small enough to effectively penetrate into these gaps.
This can cause problems due to the onset of thickening of the composition before it has sufficiently penetrated the pores and fractures of the formation.
If the composition becomes too thick to pump properly the sealant composition may not be correctly placed in all the voids before it sets.
In addition, the subterranean formations may have temperatures higher than surface conditions which lead to even higher reaction rates between the calcium carbonate and the silicate solution.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0031]To demonstrate that the system sets to a solid 30 g of calcium carbonate with a mean particle size of 70 nm (Socal® 31) is mixed in a Waring blender with 100 g of the sodium metasilicate solution, which contains 30 g sodium metasilicate and 70 g distilled water. The solids disperse easily in the solution and the resulting suspension is poured into a container. After 3 hours at room temperature the suspension had set into a solid homogenous mass. No excess fluid is present on the top of the solid.

example 2

[0032]To demonstrate the difficulty in retarding the calcium carbonate / sodium metasilicate system five samples were prepared using no retarder or a different conventional cement retarder in the suspension. 0.1 g of an antifoam and an amount of cement retarder as indicated below is added to 100 g of a sodium metasilicate solution, containing 30 g sodium silicate and 70 g water. 30 g of calcium carbonate with a mean particle size of 70 nm (Socal® 31) is added to the solution and mixed in a Waring blender. The time for the system to set as a function of retarder type and concentration was determined visually at room temperature. The results are given below in Table 1.

TABLE 1Sample12345Sodium Metasilicate100g100g100g100g100gsolutionCalcium carbonate30g30g30g30g30g(Socal ® 31)Antifoam0.1g0.1g0.1g0.1g0.1gRetarder—SodiumCalciumBoric AcidSodiumLignosulphonateGlucoheptonateGluconateAmount of Retarder—2g1g1.5g1.5gSetting Time10min20min25min30min20min

[0033]The results show that while the conve...

example 3

[0034]To demonstrate alternative mechanisms of retardation of the calcium carbonate / sodium metasilicate system three samples were prepared using different types of calcium carbonate. 0.1 g of antifoam is added to 100 g of sodium metasilicate solution, which contains 30 g sodium silicate and 70 g water. 30 g of calcium carbonate as indicate below is added to the sample and mixed with a Waring Blender. A surfactant is added to the sample containing the Socal® 312 calcium carbonate to help disperse the hydrophobically modified calcium carbonate in the solution. The setting time is determined visually at room temperature for each sample. The results are given below in Table 2.

TABLE 2Sample678Calcium carbonateSocal ® 31Socal ® 312Socal ® 90A(30 g)(30 g)(30 g)Particle size70nm70nm250-300nmHydrophobic coatingNoYesNoSodium metasilicate100g100g100gsolutionAntifoam1g1g1gSurfactant—2g—Setting Time30min85min120min

[0035]The results show that the setting time of the system can be lengthened by ei...

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Abstract

A sealant composition for use in subterranean wells comprising an alkali metal silicate and a calcium containing inorganic compound wherein the particles of the calcium containing compound have a mean particle size that is submicron.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001]This application claims the benefit of EP Patent Application 07119640.6 filed Oct. 30, 2007, entitled “Sealant Composition.”TECHNICAL FIELD [0002]This invention relates to a sealant fluid, in particular a composition comprising an alkali metal silicate solution and a calcium-containing inorganic compound that can be used to seal narrow cracks and pore spaces of subterranean wells.BACKGROUND ART [0003]Sometimes in subterranean wells it is necessary to plug small voids generally to prevent unwanted fluid flow. These voids may be cracks in the cement, or microannuli between the casing and the cement or between the cement and the formation. These voids could also be pore spaces between gravel in gravel-packs in zones that are producing too much water to remain economic. A common method of plugging these voids is to inject a cement formulation where the cement is made from micro-fine cement particles (see p 247 Well Cementing, 2nd Edition, E....

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): E21B33/13C09K8/74
CPCC04B20/1018C04B28/26C09K8/46C09K8/506C09K2208/10C04B14/28C04B20/008C04B2103/40C04B2103/50C04B22/064Y10S507/906Y10S507/902
Inventor JAMES, SIMONMICHAUX, MICHEL
Owner SCHLUMBERGER TECH CORP